The invention concerns a ceramic valve for internal combustion engines whose spring retainer is frictionally linked to the valve stem.
Ceramic engine valves are known from EP-A-0249503. From this, the valve stem is provided with an annular groove at the connecting location to the spring retainer and is surrounded by a longitudinally split collet with a conical outer profile. On its inner wall, the collet has a protuberance which engages in the groove of the valve stem. The spring retainer has a conical bore which interacts with the conical outer wall of the collet so as to provide a positive connection. In order to avoid partial stress cracks in the region of the groove in the valve stem, a soft metal coating is provided at least between the collet and the valve stem. The coating alleviates stress fractures in the cylindrical part of the valve stem but not in the region of the groove. The invention is intended to provide a remedy in this respect.